One well known design of a magnetic disk file data storage facility employs interchangeable, replaceable disk packs containing a plurality of magnetic disks. The disks are accessed by head arm assemblies mounted to a carriage that is actuated by a voice coil motor. The head assemblies, head carriage and voice coil motor are disposed in a housing external to the disk pack.
In this type of design, the spindle assembly is bolted to the baseplate. The interchangeable disk pack, which contains the hub and disks, is removably attached to one end of the spindle shaft, with the spindle drive pulley attached to the other end. Spindle bearings are located near the ends of the spindle housing, thus leaving a length of unsupported shaft. The head carriage assembly is mounted to the baseplate through ways and rails.
An advanced design of a disk file facility, as disclosed in U.S. Pat. No. 3,786,454, utilizes an interchangeable sealed cartridge that encloses magnetic disks, accessing head arm assemblies, a movable head carriage, a drive spindle for rotating the disks, and a common frame structure to maintain alignment between the cartridge components. This design provided an improvement over the aforementioned system in that the same accessing head is associated with the same disk surface so that the same relationship is maintained for the repetitive accessing accomplished between each head and disk surface. This arrangement allows increased track density as well as greater bit density on each disk surface thereby realizing improved data storage capacity while utilizing less physical space.
An improved disk storage apparatus is disclosed in U.S. Pat. No. 4,034,411 in which the disk storage apparatus comprises an enclosure within which the magnetic heads and disks are enclosed with the head carriage and a linear actuator coil, that is permanently attached to the carriage within the enclosure. In this apparatus, the generally difficult mechanical coupling required between the head carriage and the voice coil is alleviated, resulting in a decided improvement in alignment between the accessing heads and the rotating disks.
However, as more data is packed into lesser space in rotating disk file systems, the apparatus becomes more sensitive to mechanical resonances, thermal variations and contaminated air, which could lead to erroneous readout of data.
In copending application Ser. No. 838,346, filed Sept. 30, 1977, entitled "Disk File with Symmetrical Hollow Base," and assigned to the same assignee, there is disclosed a disk file in which voice coil actuators are mounted within a symmetrical base. A neutral plane divides opposing walls of the base into symmetrical parts. A stack of disks is coupled for rotation to a spindle, with the spindle axis being perpendicular to the neutral plane, while the center of gravity of the disk stack is substantially coincident with the neutral plane. When two voice coils are used, they are disposed diametrically about the disk stack and are offset equal distances from the neutral plane.
The present application discloses and claims an improved implementation of the type of disk file disclosed in copending application Ser. No. 838,346.